Low-Volume Road WMA Mixtures: Moisture Susceptibility of Mixtures Containing Coal Ash and Roofing Shingle with Moist Aggregate

Abstract

The objective of this study was to evaluate the laboratory moisture susceptibility of low-volume hot mix asphalt (HMA) and warm mix asphalt (WMA) mixtures containing moist aggregates and recycled materials, such as manufactured roofing shingles and coal ash material. These materials were tested after short- and long-term aging procedures. The test properties of these mixtures included indirect tensile strength (ITS), the tensile strength ratio (TSR), and the flow value of virgin and aged specimens. The experimental design included two percentages of coal ash (10 and 5% by weight of the aggregate), two roofing shingle contents (5 and 3% by weight of the aggregate), three WMA additives (Asphamin, Sasobit, and Evotherm), two antistripping agents (hydrated lime and one liquid antistripping agent), and two aggregate sources. A total of 72 mixtures were designed and a total of 416 ITS specimens were tested for short- and long-term aged procedures in this study. The test results indicated that the dry and wet ITS values of low-volume mixtures containing moist aggregate generally satisfied the demand of pavement without requiring additional treatment. Mixtures containing hydrated lime, in general, showed a better moisture resistance than liquid ASA for WMA mixtures. Moreover, the addition of WMA additives in the low-volume mixture was effective and generally showed a similar moisture resistance to HMA, except for when using Asphamin and liquid ASA simultaneously. Research results also indicated that the utilization of recycled coal ash and roofing shingles significantly improved moisture resistance of HMA and WMA mixtures.